Check that your RAM isn't filling up. If it is, adding more will immediately benefit you.

If RAM isn't filling up, I would focus on overclocking the processor. The 3770 (is it a K-model? You need a K-model for overclocking) should be decently overclockable (don't count on cutting loading times in half though).

An SSD for Windows won't make your Photoshop edits any faster. It'll make Windows boot faster and programs installed on the SSD will load faster (which in itself is very nice), but it doesn't affect heavy-duty computations such as image editing, since you already have an SSD as scratch disk.